Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$86.97	6.206%	$92.3674	$92.37	$92.35	$92.40
Purchase #2	$15.60	12.758%	$17.5902	$17.59	$17.60	$17.60
Purchase #3	$55.29	9.404%	$60.4895	$60.49	$60.50	$60.50
Purchase #4	$45.41	13.508%	$51.544	$51.54	$51.55	$51.50
Purchase #5	$62.38	13.437%	$70.762	$70.76	$70.75	$70.80
Purchase #6	$68.82	5.694%	$72.7386	$72.74	$72.75	$72.70
Purchase #7	$157.96	9.534%	$173.0199	$173.02	$173.00	$173.00
7 purchase totals =	$492.43		$538.5116	$538.51	$538.50	$538.50